Control of electric switches



Aug 7, 1945. T. R. COGGESHALL. 3 9

CONTROL OF ELECTRIC SWITCHES Filed Nov. 29, 1945 Fig. I.

His Attorney.

Patented Aug. 7, 1945 CONTROL OF ELECTRIC SWITCHES Thellwell R.Coggeshall, Bala Cynwyd, Pa., assignor to General Electric Company, acorporation of New York Application November 29, 1943, Serial No.512,179

11 Claims.

My invention relates to improvements in the. control of electricswitches and more particularly circuit breakers, and especially circuitbreakers whose operating mechanisms are fluid pressure actuated and arenot inherently tripfree.

Some fluid pressure actuated circuit breaker operating mechanisms arenot trip-free as long as the fluid pressure actuating means isenergized. This is more or less immaterial provided the circuitcontrolled by the circuit breaker In accordance with my invention, Iprovide, for

' a fluid pressure actuated circuit breaker, an imis normal at the timethe closing operation is performed. In usual operation, however, thecircuit breaker is opened in response to a fault. In order to restoreservice, it is important that the circuit breaker be reclosed as quicklyas possible. Usually, at least two reclosures are attempted. Obviously,in order to avoid damage to the circuit breaker and connected apparatus,the circuit breaker, must be free to open whenever it is closed on afaulty circuit. It is, therefore, necessary that the fluid pressureoperated proved trip-free and pump-free control arrangement embodying avalve operating means and control therefor for quickly deenergizing thefluid pressure actuating means when the circuit breaker is closed andregardless of the condition of the circuit at the time of closure of thecircuit breaker. Further in accordance with my invention, I provide, fora fluid pressure actuated circuit breaker, an improved controlarrangement whereby successive reclosures of the circuit breaker on afaulty circuit cannot be accomplished by the operator withoutpremeditated action on his part after each reclosure.

My invention will be better understood from the following descriptionwhen considered in cononly one closure of the circuit breaker. In othermeans either in response to the mere closing ofthe circuit breaker whilethecircut is normal or in response toabnormal circuit conditions at thetime the circuit breaker isclosed. A further object of my invention isto provide an improved circuit breaker control arrangement embodying aminimum number of auxiliary relays and the like o as to expedite thedeenergizihg action of the fluid pressure actuating means. these andother objects of my'invention will appear in more detail hereinafter.

appended claims.

In the accompanying sheet of drawings, Fig.

'l'diagrammatically illustrates a switch control arrangement embodyingmy invention and Fig. 2 diagrammatically illustrates modification of apart of the embodiment of my invention shown in Fig. 1.

In Fig. 1 of the accompanying-sheet oi drawings, I have illustrated anembodiment of my invention in a control arrangement for an electricswitch such as a circuit breaker l whose operating mechanism 2 is fluidpressure actuated to close the circuit breaker. The circuit breaker l isschematically illustrated as a three-pole switch which is biased to thecircuit open position by suitable means indicated as a, spring 3. Also,the circuit breaker is illustrated as arranged to control a circuitcomprising conductors 4, 5 and 6. As shown in elevation; the operatingmechanism 2 is :of the roller toggle type disclosed and claimed in acopending application of Nelson H. Westervelt, Serial No. 512,185, filedconcurrently herewith and assigned to the assignee of the presentapplication. This operating mechanism comprises an operating lever I andan operating crank 8. The lever I is mounted on the stationary pivot 9and pivotally connected at It to, a, circuit breaker operating rod ll,indicated schematically in part by the dash-dot line H. For actuatingthe lever 'l clockwise to close they circuit breaker l, the operatingcrank 8 is mounted on a stationary pivot l3 and provided at its free endwith a'roller ll mounted on a pin I5. The roller ll engages the rollerl6 mounted on a pin I! in the end of the operating lever I oppositeitsattachment to the operating rod I l. t

For holding the operating mechanism 2 in the switch closed positionillustrated, there is provided a prop or latch iI which. as shown, ismounted on a stationary pivot II, and, for reduction of friction load isarranged to engage a second roller mounted on the pin II and similar tothe roller II. It will be obvious that the operating mechanism describedis free to collapse upon a predetermined counterclockwise movement ofthe prop II and thereby to allow the opening of the circuit breakerprovided there is no support or force against the roller II to hold itin the illustrated position when the prop II is moved out of holdingengagement with its mociated roller.

For actuating the prop II in the'tripping direction counterclockwise .asillustrated, suitable electromagnetic means comprising a winding II isprovided. As shown, the tripping winding 2| is arranged to be energizedin response to the operation of a protective relay 2| or a trippingcontrol switch 22. The protective relay II is illustrated simply as. anovercurrent relay connected to be energized from a current transformerII in the circuit conductor 4. It will be understood, ot course, thatany number or relays may be employed in accordance with the art ofcircuit protection. Also as shown, the circuit of the winding II, whichincludes conductors II and II, may also include the contacts II of a circuit breaker a auxiliary switch which is closed when the circuit breakeris closed and open when the circuit breaker is open.

For actuating the operating mechanism I to close the circuit breaker I.I provide fluid pressure actuated means comprising a cylinder 11 withinwhich is slidably mounted a piston II carrying a piston rod 29. Thisrod, on its upstroke under the admission of fluid under pressure beneaththe piston II, engages the roller II whereby to move the crank Iclockwise until the parts of the operating mechanism 2 are positioned asshown in the drawing with the circuit breaker I closed. The prop II,unless its winding II is energized, drops in under its associated rollerto hold the circuit breaker closed after the piston rod It returns toits lower position. While any suitable fluid may be provided to raisethe piston II, it is usual to use air under the desired pressure in areceiver or tank Ill from which the air is supplied to the cylinder 21through control valve means II embodying my invention. On the upstrokeoi the piston II,

suitable energy storing means, such as springs II, are compressed toeilect the down or return stroke of the piston II to the lower positiondump valve II, the air under pressure opens an admission valve IImounted in the head of the dump valve 33 to uncover ports therein forthe admission of air to the cylinder 21. The admission valve II isbiased to the closed position by a spring 31 which becomes so compressedthat when air is subsequently exhausted from the space II, the valve IIquickly closes the ports in the dump valve II, which then moreeliectively moves to uncover the ports IL In accordance with myinvention, the control valve means II is electromagnetically actuated,and, as shown, it is or the pilot diilerential type embodying a pilotvalve II and a main valve means such as a piston valve II. Also. asshown, it includes an exhaust valve II for release oi air to atmospherefrom behind the dump valve II and from the delivery portion ll oi thevalve body. For pressure equalization on the inlet side oi the valve II,the main valve II is provided with a bleed hole '42. The pilot valve IIseats on the upper side oi! the main valve II, where it is maintained.closed by the entrapped pressure above it. This pilot valve is raisedagainst the bias of suitable energy storing or valve closing means, suchas a kick-oil spring II.

For opening the pilot valve II, I provide electromagnetic meanscomprising an armature II, a magnetic housing II, a pole piececomprising magnetic elements II, I1 and II, and a valve opening windingII. As illustrated, the electromagnetic means is of the plunger andsolenoid type with the armature II suitably connected to the valve II asby a rod II. In'order to hold 85 the armature II in the attractedposition after shown. This downstroke operation follows the cutting oi!oi the air supply by the control valve Ii so that the ,air in thecylinder 21 can be quickly exhausted to atmosphere through the medium ofa dump valve II which uncovers an exhaust port II. This dump valve isdisclosed.

and claimed in my copending application, Serial No. 512,180, fliedconcurrently herewith and assigned to the assignee of the presentapplication.

In order to avoid pressure above the piston It on the upstroke and alsoto have it return freely under the bias of the springs II. the cylinderII through the valve Ii to the back or the dump valve II. This valve IImoves to the left against the bias of a spri g Iland closes the exhaust"port I. coincidentally with the closing of the it is moved to thisposition, the pole piece magnetic element 4] is, in accordance with myinvention, of permanently magnetic material, examples of which are wellknown to the art. Thus. it may be of the permanently magnetic alloy typeknown as Alnico. The prevailing pressure above the valve II inconsequence oi the bleed hole I2 keeps this valve closed. However, whenthe pilot valve II is opened in response to the attraction oi thearmature II, this pressure is exhausted to the low pressure space Ii andto the atmosphere through exhaust ports II of the exhaust valve II. Theexcess of pressure is therefore shifted from above the main valve II tobelow it so that it is lifted against the bias of a spring II whichtends to-move the armature II to the unattracted position.Simultaneously with the opening of the main valve II, the exhaust valve40, which is held open by the main valve 39 pressing on the hollow stemII of the valve I0 against the bias of a spring II, is permitted toclose and thus seal the outlet or delivery portion II o! the controlvalve II against loss to atmosphere. The hollow stem II oi! the exhaustvalve II is provided with one or more equalizing exhaust ports II and anuplift piston II.

For closing the circuit breaker i, I provide, in accordance with myinvention, a closing control circuit for the valve opening winding II.As shown, this circuit includes a closing control switch II, thecontacts." of a minimum pressure switch II which opens when the pressurein the tank II falls'below a predetermined minimum value, a conductorII, b auxiliary switch contacts II oi the circuit breaker l, a conductorII, the contacts I! or a short time delay circuit opening relay II whosewinding'II is energized upon closure of the closing control switch II, aconductor II, the valve opening winding II,

and a conductor 88. The opening of the circuit breaker closing controlcircuit by the slightly delayed contacts 62 of the relay 83 insures apositive opening of the control valve 3| in response to the energizationof its winding 48 and also prevents reclosure of the circuit breaker aslong as the control switch 56 is kept closed. In other words, with asingle closure of the control switch 58, only one closure of the circuitbreakerfl can be effected.

In accordance with my invention, I provide means for quickly returningthe piston 28 to the down position shown because the circuit breakermechanism 2, although of itself inherently triptree, cannot move to theopen circuit position as long as air pressure below the piston 28 keepsthe piston rod 29 pressing against roller I4 with enough force tomaintain the mechanism 2 with its parts positioned as shown in thedrawing. For this purpose, I provide means for effecting the closure ofthe valve means 3| to cut off the pressure supply at the end of thepiston stroke when the circuit breaker is fully closed. As shown, thismeans comprises a valve closing winding 61 so wound and connected to beenergized that its polarity is opposite to the polarity of the openingwinding 49 and is such as to neutralize the holding flux of thepermanent magnet 47 whereby to release the plunger 44 for the valveclosing movement. In order to insure the energization of the valveclosing winding 61 at the proper moment, the circuit of this winding iscontrolled by a limit switch 68 which is actuated to the closed positionin response to the movement of the piston 28 so as to close its contacts69 in the circuit of the winding 61 when the breaker is fully closed. Asshown, the circuit of the valve closing winding 61 includes the contacts69 of the cutoff or limit switch 68, the conductor 10, and the valveclosing winding 61.

Also in accordance with my invention, in order to insure a'fast orearlier opening of the circuit breaker I when it is closed during anabnormal circuit condition, I provide means for substantiallysimultaneously tripping the circuit breaker and effecting the closing ofthe valve means 3|. As shown, this means comprises a valve closingwinding H which is independent of the winding 51 and which is wound andconnected to be energized to have a polarity such as to neutralize themagnetic holding effect of the permanent magnet 41 whereby to releasethe plunger 44 to close the valve 3| and the trip circuit comprising thetripping winding of the circuit breaker mechanism. The circuit for theclosing winding Assuming the parts as positioned in the drawing, thenwhen closure of the contacts of the relay 2| or the control switch 22 iseffected, the circuit of the trip coil 20 is energized to move the latch|8 to the releasing position. The circuit breaker I is then opened bythe bias of the spring 3. The circuit breaker is, of course, free toopen without opposition from the piston 28 which returned to its lowerposition at the end of the preceding closing operation. At the same timethat the trip coil 20 is energized, the valve closing winding H is alsoenergized, but since the valve 39 is already closed, nothing happens atthis time in consequence of this energization.

Upon the opening of the circuit breaker, the a auxiliary switch contacts26 are opened and the -b auxiliary switch contacts 60 are closed. Whenit is desired to close the circuit breaker, the control switch 38 isclosed, and if the pressure in the tank 30 is suiiicient to maintain thelow pressure interlock switch contacts 51 closed, then the circuit ofthe opening winding 49 is completed and will be maintained until theshort time delay circuit opening relay 63 opens its contacts 82. Uponenergization of the valve opening winding 49, the armature 44 is movedto the attracted position. During this movement it opens the pilot valve38 and thereby exhausts pressure to air by way of the outlet portion 4|and the ports 40 of the valve 3| and thus effects the opening oi themain valve 38 and the closing of the exhaust valve 40. Admission of airunder pressure back of the dump valve 33 seats this valve against thebias of the spring 35 whereupon its associated admission valve 36 isopened against the bias of its spring 31. This admits air under pressurebelow the piston 28, which is thus caused to travel upward against thebias of the spring 32 to engage the roller l4 and the crank 8 andthereby turn this crank and the operating lever l1 clockwise until theprop latch I8 is free to fall under the roller and maintain the circuitbreaker I in the closed position.

As soon as the piston 28 reaches the end of its upstroke with thebreaker fully closed, the limit switch 68 closes its contacts 69 therebycompleting the circuit of the valve closing or neutralizing winding 61.With the neutralization of the holding effect of the permanent magnet41, the plunger armature 44 is rapidly actuated under the bias ofsprings 43 and 5| to the unattracted position to effect the closing ofthe pilot valve 38 and the main valve 39 whereby to shut off the supplyof air to the cylinder 21. At the same time, the exhaust valve 40 isopened and the pressure back of the-dump valve 33 relieved so that thisvalve can open under the bias of its spring 35 to dump the air in thecylinder through exhaust port 34. With the quick release of the pistonrod 29 from its holding position under the roller M, the circuit breakeroperating mechanism is restored to its inherently trip-free condition.

If the breaker is closed on a faulty circuit, the operation of aprotective relay, such as the overcurrent relay 2|, or other trippingmeans, such as the switch 22, is immediately effective to cause theopening of the circuit breaker. In fact, if during the closingoperation, current above the pick-up value of the relay 2| flows in thecircuit 4, 5, 6 upon the initial touching of the circuit breakercontacts before the operating mechanism is fully latched, the completionof the circuit of the neutralizing closing winding H by the closing ofthe contacts of the relay 2| is effective to cause the closing of thevalve means 3| somewhat in advance of the operation of the limit switchwhich controls the closing winding 61'. It will accordingly be clearthat the circuit breaker operating mechanism is maintained in itsinherently trip-free operating condition except for the brief timenecessary to effect the closing of the valve means 3| while the pistonrod 29 is in contact with the roller I 4 in its upper or closingposition. Moreover, since the trippng or closing action of the valvemeans 3| is efiected without the action of auxiliary relays, the closingtime of this valve means is very short.

In automatic. station applications, and also when the control switch 56is of the stay-put type, it may be desirable to have the energization ofthe short time delay relay 63 controlled independently of the minimumpressure switch II, as shown, for example, in Fig. 2. In this figure,the energizing circuit of the relay 8! includes the control switch 86and a conductor 59' without passing through the contacts 51 of theminimum pressure switch 58. With this arrangement, it will be clear thatif the control switch It is closed when the minimum pressure switch itis open, the relay will be energized to open its contacts 62 and willremain energized with these contacts open as lon as the control switchII is left closed. Then, if the control switch 56 is closed and leftclosed while the minimum pressure switch is open, mere subsequent returnof pressure cannot effect a closing operation of the circuit breaker,which might happen at an inadvertent time to cause damage or even lossof life to operating personnel.

While I have shown and described my invention in considerable detail, Ido not desire to be limited to the exact arrangements shown, but seek tocover in the appended claims all those modifications that fall withinthe true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a control arrangement for an electric switch provided with fluidpressure actuated closing means arranged to be energized throughelectromagnetically actuated valve means from a source of fluid underpressure, a control circuit for eflecting the opening of said valvemeans, a control switch in said circuit, means connected to be energizedupon closure of said control switch for opening said control circuit apredetermined time thereafter, magnetic means for holding said valvemeans open, electromagnetic means for neutralizing the effect of saidholding means, and means for effecting the energization of saidneutralizing means during the closing of said electric switch.

2. In a control arrangement for an electric switch provided with meansfor holding the switch closed and also with a fluid pressure actuatedclosing means arranged to be energized through electromagnetically'actuated valve means from a source of fluid under pressure, a controlcircuit for effecting the opening of said valve means, a control switchin said circuit, means connected to be energized upon closure of saidcontrol switch for opening said control circuit a predetermined timethereafter, magnetic means for holding said valve means open,electromagnetic means for neutralizing the effect of said valve holdingmeans, means dependent on the completion of the action of the fluidpressure actuated means for effecting the energizetion of saidneutralizing means, and means for substantially simultaneously effectingthe energization of said neutralizing means and the release of saidswitch holding means.

8. In a control arrangement for an electric switch provided with meansfor holding the switch closed and also with a fluid pressure actuatedclosing means arranged to be energized from a source of fluid underpressure, means Ior controlling the flow or fluid from said source tosaid actuated means and from said actuated means comprising anelectromagnetically actuated valve provided with an armature movable tothe attracted position to open the valve, energizing winding means foreffecting movement of the armature to the attracted position, magneticmeans for holding the armature in the attracted position, winding meansfor neutralizing the holding effect of said magnetic means, a controlswitch, a control circuit including said control switch and saidenergizing winding means, a time delay circuit opening relay having itscontacts in said control circuit and an actuating winding connected tobe energized upon closure of the control switch, and means dependent onthe completion of the action of the fluid pressure actuated means foreffecting the energization of said neutralizing winding means.

4. In a control arrangement for an electric switch provided with meansfor holding the switch closed and also with a fluid pressure actuatedclosing means arranged to be energized from a source of fluidunder'pressure, means for controlling the flow of fluid from said sourceto said actuated means and from said actuated means comprising anelectromagnetically actuated valve provided with an armature movable tothe attracted position to open the valve, energizing winding means foreffecting movement of the armature to the attracted position, magneticmeans for holding the armature in the at tracted position, winding meansfor neutralizing the holding effect of said magnetic means, a controlswitch, a control circuit including said control switch and saidenergizing winding means, a time delay circuit opening relay having itscontacts in said control circuit and an actuating winding connected tobe energized upon closure oi. the control switch, means dependent on thecompletion of the action of the fluid pressure actuated means foreffecting the energization of said neutralizing winding means, and meansfor substantially simultaneously effecting the energization of saidneutralizing winding means and the release of said switch holding means.

5. In trip-tree and pump-free control arrangement for an electriccircuit breaker provided with pneumatically actuated closing meansarranged to be energized from a source of air under pressure, means forcontrolling the flow of air from said source to said actuated means andfrom the actuated means to atmosphere comprising an eletromagneticallyactuated valve provided with an armature movable to the attractedposition to open the valve, a valve opening winding operative whenenergized to effect movement of the armature to the attracted position,a permanent magnet for holding the armature in the attracted position, avalve closing winding operative when energized to neutralize the holdingeffect of said permanent magnet, a control switch, a control circuitincluding said control switch and said valve opening winding, a timedelay circuit opening relay having its contacts in said control circuitand an actuating winding connected to be energized upon closure of thecontrol switch, and means dependent on the completion of the action ofthe pneumatically actuated means for effecting the energization of saidvalve closing winding.

6. In trip-free and pump-free control arrangement for an electriccircuit breaker provided with fluid pressure actuated closing meansarranged to be energized from a source of fluid under pressure, meansfor controlling the flow of fluid from said source to said actuatedmeans and from said actuated means comprising an electromagneticallyactuated valve provided with an armature movable to the attractedposition to open the valve, a winding operative when energized to effectmovement of the armature to the attracted position, magnetic means forholding the armature in the attracted position, winding means operativewhen energized to neutralize the holding effect of said magnetic means,a control switch, a control circuit including said control switch andsaid operating winding, a time delay circuit opening relay having itscontacts in said control circuit and an actuating winding connected tobe energized upon closure of the control switch, means dependent on thecompletion of the action of the fluid pressure actuated means foreffecting the energization of said winding means, and means forsubstantially simultaneously tripping the circuit breaker and effectingthe energization of said winding means.

7. In trip-free and pump-free control arrangement for an electriccircuit breaker provided with pneumatically actuated closing meansarranged to be energized from a source of air under pressure, means forcontrolling the flow of air from said source to said actuated means andfrom the actuated means to atmosphere comprising an electromagneticallyactuated valve provided with an armature movable to the attractedposition to open the valveya valve opening winding operative whenenergized to effect movement of the armature to the attracted position,a permanent magnet for holding the ar-.

mature in the attracted position, valve closing winding means operativewhen energized to neutralize the holding efiect of said permanentmagnet, a control switch, a control circuit including said controlswitch and said valve opening windin a time delay circuit opening relayhaving its contacts in said control circuit and an actuating windingconnected to be energized upon closure of the control switch, meansdependent on the completion of the action of the pneumatically actuatedmeans for efieoting the energization of said valve closing windingmeans, and means for substantially simultaneously tripping the circuitbreaker and efiecting the energization of said valve closing windingmeans.

8. In a control arrangement for an electric switch provided with fluidpressure actuated closing means arranged to be energized from a sourceof fluid under pressure, valve means comprising a member movable in onedirection to a predetermined position to control the flow of fluid fromsaid source to said actuated means and in the opposite direction fromsaid position to control the flow of fluid from said actuated means,means for eii'ecting the movement of said member in said one directionto said predetermined position, means tending to move said member in theopposite direction, means for holding said member in said predeterminedposition'against the effect of said motion tending means; and means forneutralizing the efiect of said holding means during the closingoperation of said electric switch.

9. In a control arrangement for an'electric switch provided with meanstor holding the switch closed and also with fluid pressure actuatedclosing means arranged to be energized from a source of fluid underpressure, valve means comprising a member movable in one direction to apredetermined position to control the flow of fluid from said source tosaid actuated means and in the opp site direction from said position tocontrol the flow of fluid from said actuated means, means for effectingthe movement of said member in said one direction to said predeterminedposition, means tending to move said member in the opposite direction,means for holding said member in said predetermined position against theefiect of said motion tending means, means for neutralizing the effectof said holding means during the closing operation of said electricswitch, and means for substantially simultaneously neutralizing theefiect of said member holding means and the release of said switchholding means.

10. In a control arrangement for an electric switch provided with fluidpressure actuated closing means arranged to be energized from, a sourceof fluid under pressure, electromagnetically actuated valve meanscomprising an armature movable to the attracted position to control theflow of fluid from said source to said fluid pressure actuated means andto the unattracted position to control the flow of fluid from said fluidpressure actuated means, a control circuit for effecting theenergization of said electromagnetically actuated valve means to movesaid armature to the attracted position, a control switch in saidcontrol circuit, means connected to be energized upon closure of saidcontrol switch for subsequently opening said control circuit, meanstending to move the armature to the unattracted position, magnetic meansfor holding the arma ture in the attracted position after the opening ofthe control circuit, magnetic means for neutralizing the efiect of saidholding means, and means for effecting the energization of saidneutralizing means during the closing of said electric switch.

11. In a control arrangement for an electric switch provided with fluidpressure actuated closing means arranged to be energized throughelectromagnetically actuated valve means from a source of.fluid underpressure; a control circuit for efiecting the opening or said valvemeans, a control switch in said circuit, means connected to be energizedupon closure of said control switch for opening said control circuit atpredetermined time thereafter, magnetic means for holding said valvemeans open, electromagnetic means for neutralizing the effect of saidholding means, and means for effecting the energization of saidneutralizing means within the region of the closed position of saidfluid pressure actuated closing means.

THEILWELL R. COGGESHAIL.

